1. Field of the Invention
The present invention relates to a VDSL transmission system in which power control is used to reduce FEXT, a modem for use in a VDSL transmission system, and a method of reducing FEXT in a VDSL transmission system by using power back-off.
2. Discussion of the Related Art
One problem, frequently encountered with VDSL transmission systems, is that upstream FEXT produced by system users having short wires can be very strong. This severely limits the performance for users with longer wires. Users having shorter wires get high bit rates whereas users having longer wires get low bit rates, or possibly a zero bit rate. In extreme cases it may happen that users with wire lengths greater than 1000 meter cannot transmit data upstream.